Early Journal Content on JSTOR, Free to Anyone in the World This article is one of nearly 500,000 scholarly works digitized and made freely available to everyone in the world by JSTOR. Known as the Early Journal Content, this set of works include research articles, news, letters, and other writings published in more than 200 of the oldest leading academic journals. The works date from the mid-seventeenth to the early twentieth centuries. We encourage people to read and share the Early Journal Content openly and to tell others that this resource exists. People may post this content online or redistribute in any way for non-commercial purposes. Read more about Early Journal Content at http://about.istor.org/participate-istor/individuals/early- journal-content . JSTOR is a digital library of academic journals, books, and primary source objects. JSTOR helps people discover, use, and build upon a wide range of content through a powerful research and teaching platform, and preserves this content for future generations. JSTOR is part of ITHAKA, a not-for-profit organization that also includes Ithaka S+R and Portico. For more information about JSTOR, please contact email@example.com. SOCIETY OF MICROSCOPISTS. 315 THE CRYSTALLOGRAPHY OF BUTTER AND OTHER FATS. By Thomas Taylor, M.D., Microscopist U. S. Department of Agriculture, Washington, D. C. PLATES I. AND II. CRYSTALLINE FORMATIONS OF BUTTER AND FATS. Figs, i, 2, 3 and 4. Represent primary crystals of butter, X80 to no. Figs. 5 and 6. Secondary crystals forming within primary crystals. Figs. 7 and 8. Secondary crystals which have separated from the pri- mary forms. XSotoiio. Figs. 9, 10 and 11. Tertiary crystals of butter. X80 to 140. Fig. 12. Tertiary passing into the amorphous. X140. Figs. 13, 14, 15 and 16. Represent oleomargarine. X80 to no. Fig. 17. Oleo, X140. This crystal is not found in unboiled oleomarga- rine. Fig. 18. Oleo in its second stage, as seen in oleomargarine as sold. Figs. 19 and 20. Common lard. X140 to 400. Figs. 21, 22, 23 and 24. Crystals of beef-fat from various tissues of the ox. (Omentum, kidney, marrow of the femur, and round.) PLATE III. CRYSTALLINE FORMATIONS OF BUTTER. Figs, i, 2, 3, 6, 8, 9, 12 and 14. Primary crystals of normal butter. Xgo to no. Figs. 4, 7 and 10. Primary crystals showing "secondaries" forming. Figs. 13 and 15. Secondary crystals of butter. X8oto 140. Figs. 5 and n. Tertiary crystals of butter. X80 to 140. 3l6 PROCEEDINGS OF THE AMERICAN PLATE IV. CRYSTALLINE FORMATIONS OF OLEO AND BUTTER. Figs, i, 2, 4 and 11. Crystals of boiled oleo (Armour). X70 to 140. Figs. 3, 5, 6, 7, 8 and 9. Crystals of boiled oleo in process of decay. Such forms are frequently observed in oleomargarine. X140. Fig. 10. The butter crystal as photographed by Detmers. Fig. 12. A crystal of oleo and lard made by Prof. Weber, which he says cannot be distinguished from that of pure butter. (See Figs. 10 and 14.) Figs. 13 and 15. Crystals of boiled butterine as prepared by Prof. Weber and photographed by Prof. Detmers, repre- senting the butter crystal according to Prof. Weber. Fig. 14. The true butter crystal, photographed by the late Dr. Bernard Persh. Compare this plate with the transition stages of butter crystals, Plate I. PLATE V. CRYSTALLINE FORMATIONS OF OLEO AND OLEO- MARGARINE. Fig. I. Boiled oleo by plain light, exhibiting spines. X140. Fig. 3. Boiled oleo by polarized light, showing a cross. X140. Figs. 2, 4, 5, 6, 9, 11, 12, 13, 14 and 15. General appearance of oleomar- garine as sold in the market. X75 to 1 10. Fig. 7. Armour's oleomorgarine boiled and cooled. X140. Fig. 10. A specimen of oleomargarine composed mostly of stearine and cottonseed oil. Xno. Fig. 8. Boiled butterine (Armour's make), showing the oleo crystals. The above crystals were all photographed by polarized light, except in the case of Fig. i, which was by plain light. Plate I. CRYSTALLINE FORMATIONS OF r.UTTLR AND FATS. Plate II CRYSTALLINE FORMATION OF BUTTER AND FAT. as seen by polari/ed light and selenste plaie r.rAnm.(^0/ • •(.» LiThtJl LtlCWTT <^'irriN« CO Kf Plate III. CRYSTALLINE FORMATIONS OF BUTTER. I EMO. CO., N. V. Photocrfciib-l bT P(.r»ii, Wftliual«7 »utl (ift^ojo* Plate IV. CRYSTALLINE FORMATIONS OF "OLEO" & BUTTER. MO%» CNa. C0-« N. V. Ptrih and Detmert. Pbotofi. Plate V, CRYSTALLINE FORMATIONS OF "OLEO" & OLEOMARGINE. BOILED AND RAW. mcsj tNQ. CO.. N. V Plate VT. CRVSTALLtNE FORMATIONS OF LARD AND OTHER FATS. 2 MOtll tNO <LU., N. V. SOCIETY OF MICROSCOPISTS, 31/ PLATE VI. CRYSTALLINE FORMATIONS OF VARIOUS FATS. Figs, i and 3. Respectively, primary and secondary crystals of loon fat. Xiio. Figs. 2 and 8. Primary and secondary crystals of musk-rat fat. The primary (No. 2) are always very small, measuring about three one-thousandths of an inch in diameter. Fig. 4. Crystals of oleo. X 140 diameters. (Extract of beef-fat.) Fig. 5. Crystals of common lard by plain light. X400. Fig. 6. Secondary crystals of butter. Xno. Fig. 7. Crystals of beef fat. X140. Fig. 9. Crystals of deer fat. X140. Fig. 10. Lard by plain light. X140. Fig. II. Crystals of the solid fat of cottonseed oil. Xno. Fig. 12. Neutral lard crystals, immature. X140.